1. Field of the Invention
The present is related to an anti leakage device for lubrication oil in a fan and particularly to a device preventing the lubrication oil in a bearing of a fan from leaking.
2. Brief Description of Related Art
Due to running speed of the computer getting faster and resulting in more heat being generated, cooling device has become one of essential parts arranged in the computer for dissipating the heat effectively. The cooling fan is convenient while in use and cheap in cost so that it has become the most popular cooling device. A good cooling fan depends on good quality of the motor completely and an unstably running motor seriously affects the normal operation of the whole cooling fan. Further, the bearing is a key influencing quality and stability of the motor.
The ball bearing has been adopted in the conventional fan motor at the time of the fan motor being used at the very beginning. But, the metal balls, which are usually 8 to 12 pieces disposed and turning in the bearing ring connecting with the rotational shaft, are not complete round due to fabricating problems. Nevertheless, the balls and the bearing ring may be a little deformed under preload and a phenomenon of runout may generate during running in case of the roundness of the metal balls or the bearing ring is not so flawless. The phenomenon of runout is not synchronous with rotation of the motor and this type of motor is called nonrepeatable runout (NRRO).
Another restriction to ball bearing type motor is in that it is not possible for the motor to offer a desirable speed increase. When the ball bearing type motor provides a certain high speed, temperature rise resulting from the high speed will affect quality of lubrication oil and it is unable to meet the anticipated life span and reliability for a long period of time.
In the mean time, the metal balls of the ball bearing may be forced to enter the bearing ring and it results in the metal balls generating some little recesses, which provide greater possibility to occur NRRO. Accordingly, it also has greater possibility to generate noise.
Currently, self-lubrication bearing is popularly used for meeting the market of consumer electronic equipment. Due to providing a feature of high self-lubrication, the bearing is not necessary to have the aid of foreign grease for lubrication. Further, the self-lubrication bearing is provided with high load itself so that excellent performance can be obtained even under low rotational speed. In addition, providing very low surface friction coefficient, the self-lubrication bearing can offer excellent wear resistant performance under a condition of rotary movement. Moreover, it is very safe for the self-lubrication bearing being used in an environment of high or low temperature. Besides, other advantages such as low cost and occupying less space can be obtained from the self-lubrication bearing.
Furthermore, Taiwanese Patent Publication No. 86215592, entitled OIL STORAGE BEARING ASSEMBLY, discloses that the bearing assembly is mounted to a groove of a motor seat and the bearing structure includes a rotational shaft with a recess part, a sleeve being placed in the groove without engaging bolt for catching the recess part of the shaft so as to effect one side mount, and a bearing placed in the sleeve and disposed at the engaging bolt. Thus, an oil storage zone can be formed between the bearing, the sleeve and the engaging bolt for receiving a certain amount of lubrication oil and replenishing oil required by the rotational shaft during turning.
The preceding prior art further provides an alternate structure at the center of the fan blade and the alternate structure includes a first annular uneven surface and a second annular uneven surface. The first uneven surface surround the rotational shaft and the second annular uneven surface surrounds the first uneven surface next to an end of the sleeve. It is possible to prevent the oil contained in the bearing from leaking outward and provides a function of catching leaked oil by way of multiple round about paths.
However, there are problems for the above-mentioned prior art while in use. The first annular uneven surface extends outward next to outer side of the sleeve to constitute an open space and the lubrication oil can leak via the open space. As a result, unfavorable lubrication due to oil decreasing will cause high heat and damage and oily dirt may stain the multiple round about paths to affect the rotational efficiency and life span of the heat generating parts under operation of abnormal temperature.